Foot dimmer switch



E. H. PROTZ 2,809,262

FOOT DIMMER SWITCH Filed Dec. 10, 1954 INVENTOR.

E0 WARD P/Porz BY United States Patent O FOOT DIMMER SWITCH Edward H.Protz, Ann Arbor, Mich., assignor to Ca rter Parts Company, Chicago,111., a corporation of Illinois Application December 10, 1954, SerialNo. 474,344

2 Claims. (Cl. 200168) This invention relates to a foot dimmer switch ofthe type particularly but not exclusively used in the controllingcircuit of the headlights of a motor vehicle. Certain of the mechanismsemployed in practicing the instant invention are those disclosed inUnited States Patent No. 2,604,793.

The invention disclosed in said Patent No. 2,604,793 relates to amechanism whereby foot actuation of a cap member causes certain switchelements to be moved so as to effect engagement and disengagement ofcertain circult-controlling terminals. In order to protect the switchelements against failure caused by the presene of dirt and moisture theswitch elements are enclosed in a housing or casing. One wall of thecasing is open for the reception of a board or cover member. This boardor cover member carries the aforementioned terminals and is referred toas a terminal board. In order that the various terminals be suitablyinsulated from one another it has been found advisable (for reasons ofmanufacturing economy) to construct the entire terminal board out of aninsulating material such as a phenolic material. Unfortunately phenolicmaterials shrink as they age. It was found therefore that when suchmaterials were used in the construction of the terminal board the boardwould in time shrink to the extent that the joint between the board andcasing'was opened and unwanted road dust and moisture was allowed toenter the casing.

Dust and moisture also was found to enter the casing at the jointbetween the casing and previously mentioned cap member.

As distinguished from the disclosures of said Patent No. 2,604,793, thepresent invention proposes to so design and construct the assembly as toprovide a sealed switch mechanism which is dust and moisture free duringits expected useful life.

The primary object of the present invention is to provide a foot dimmerswitch wherein the switch elements are isolated from dirt and moisture.

A secondary object is to provide a foot dimmer switch wherein theterminal board can be formed entirely out of insulating material in sucha manner as to provide a tight joint between it and the switch casingthus barring unwanted road dust and moisture from the interior of thecasing.

Another object is to provide a switch wherein the terminal board can beformed entirely out of insulating material, and wherein means areprovided for sealing the joint between the terminal board and switchcasing at all times and to compensate for shrinkage of the terminalboard after its installation in the casing.

Another object is to provide a switch wherein the terminal board can beformed entirely out of an insulating material, and wherein a resilientsealing means is compressively retained between the terminal board andswitch casing to compensate for any changes in terminal board dimension.

Another object is to provide a foot dimmer switch 2 wherein the jointbetween the switch casing and footengaged member is sealed at all timesto prevent entrance of dust and moisture into the casing.

Other objects of this invention will appear in the following descriptionand appended claims, reference being had to the accompanying drawingsforming a part of this specification wherein like reference charactersdesignate corresponding parts in the several views.

In the drawings:

Fig. 1 is an elevational view of a preferred embodiment of theinvention, parts thereof being broken away to show certain details ofconstruction.

Fig. 2 is a plan view of the embodiment shown in Figure 1.

Before explaining the present invention in detail, it is to beunderstood that the invention is not limited in its application to thedetails of construction and arrangement of parts illustrated in theaccompanying drawings, since the invention is capable of otherembodiments and of being practiced or carried out in various ways. Also,it is to be understood that the phraseology or terminology employedherein is for the purpose of description and not of limitation.

Referring now to the drawings there will be seen to have been provided acasing 1 comprised of a circular body portion 2 and a tubular extension3. A footactuated cap member 4 fits over the free end of extension 3.Two apertured arms, numbered 5 and 6 in the drawings, are provided formounting casing 1 beneath an automobile foot board (not shown) in suchposition that cap member 4 projects therethrough sufficiently to permitits being depressed by pressures exerted through the foot of thepersondriving the automobile.

Between cap member 4 and tubular extension 3 there is provided aresilient sealing ring 7. This sealing ring has been found toeffectively prevent the entrance of dirt and moisture into the spacebetween tubular extension 3 and member 4.

Member 4 is interconnected with a switch actuating means indicatedgenerally by numeral 8. In the preferred embodiment this actuating meansis the same as the corresponding means disclosed in United States PatentNo. 2,604,793 to which reference is hereby made. Ac

cordingly a detailed description of this actuating means is not repeatedhere.

Actuating means 8 is arranged so as to rotate a pair of switch elements9 and 10 which are positioned on a rotor element 11. The rotor andswitch elements are preferably constructed and arranged to function inthe same manner as the corresponding elements disclosed in United StatesPatent No. 2,604,793.

Elements 9 and 10 are, through the mechanism of contact strip 15 andstuds 12, 13 and 14, designed to control current flow between theterminals 16, 17 and 18. These terminals must, of course, be insulatedfrom one another, and accordingly they are mounted on a terminal board19 which is formed of insulating material. Preferably board 19 is formedof a plastic material such as a phenolic material. Unfortunately,phenolic ma terials shrink to a certain extent as they age. It iseconoinically unfeasible to completely age the phenolic terminal boardsprior to their installation in the switch housings. It was found,however, that when the phenolic terminal boards were installed in theswitch casings while in a partially aged condition the joint between theboard and casing would open up and allow unwanted road dust to enter thecasing. Accumulation of road dust in the casing was found to clog theswitching mecha nisms and thereby cause the switch to fail.

To prevent entrance of dust into the casing there is provided aresilient ring member 20 formed of rubber or other resilient material.This ring member is positioned 011 an endless shoulder 21 formed on theinterior faces of the casing walls. An endless wall is provided at 22for retaining the ring member against movement out of engagement withshoulder 21. To securely retain board 19 in the casing there is providedon the casing wall an endless flange 23..

Assembly of the terminal board within the switch casing is such thatinitially flange 23 is formed as a straight line extension of the casingwall. Resilient ring 20 is then inserted in the groove formed byshoulder 21 and wall 22. Ring 2% is at this time in an uncompressedstate and extends beyond the upper edge of wall 22. As the next step inthe assembly operation board 19 is pressed into facial engagement withresilient element 20 to put the resilient element in compression. Whileelement 20 is still under compression flange 23 is turned down intoengagement with the exterior face of board 19. This step completes theassembly of the terminal board in the casing.

As was stated earlier, terminal board 19 is formed out of a plasticmaterial which is subject to shrinkage. Therefore, board 19 will, afterthe switch has undergone a period of use, be of a reduced thickness. Thejoint between the board and easing will not open up, however, becauseelement 2%) will compensate for the reduction in board thickness. Thus,as board 19 decreases in thickness the compressive forces on theresilient element 20 are reduced thus allowing it to expand and maintaina dust and moisture-proof seal between the terminal board and easing. Inorder for element 20 to be fully effective as a sealing medium it isinitially compressed to a greater extent than the calculated shrinkageof the terminal board. Element 20 is thereby always in compression andthe seal between the terminal board and switch casing always is closed.

The structural relationships whereby the desired sealing action ismaintained are set forth in the following claims.

Having thus described my invention, I claim:

1. A switch comprising a casing, said casing including a body portionand a tubular extension, switch elements positioned within the bodyportion, actuating means within the tubular extension and in operativeengagement with the switch elements, a cap member interconnected withthe actuating means and having wall portions thereof encircling thetubular extension, an endless resilient sealing ring positioned betweensaid wall portions and tubular extension portions, the aforementionedbody por- 4 tion being provided with an aperture in registry with theswitch elements, means forming an endless shoulder on the interior facesof the body portion walls around the periphery of the aperture, anendless groove formed in the face of said shoulder, an endless resilientexpandable gasket positioned in the groove and having an expandedthickness greater than the depth of the groove, a terminal board ofshrinkable material positioned within the aperture in facial engagementwith the resilient gasket, and flange means projecting from the bodyportion walls into compressive relation with the exterior face of saidterminal board so as to squeeze the gasket between the board andgroove-forming surfaces, whereby when the terminal board shrinks afterits installation the gasket will expand so asto maintain the sealbetween the board and easing.

2. A switch comprising a casing, actuating means extending through onewall of the casing and into the interior thereof, switch elementspositioned within the casing in operative engagement with the actuatingmeans and in registry with an opening formed in the casing, meansforming an endless shoulder on the interior faces of the casing wallsaround the periphery of the opening, endless groove formed in the faceof said shoulder, an endless resilient expandable gasket positioned inthe groove and having'an expanded thickness greater than the depth ofthe groove, a terminal board formed out of a plastic material which issubject to shrinkage during an aging period after its formation, saidboard being positioned within the aforementioned opening in facialengagement with the resilient gasket, and flange means projecting fromthe casing walls into such overlapping compressive relationship with theexterior face of said terminal board that the resilient gasket will becompressed through a greater distance than the difference in thicknessof the terminal board betweeen the time when it is formed and the timewhen it is completely aged.

References Cited in the file of this patent UNITED STATES PATENTS2,285,916 Eisner June 9, 1942 2,389,592 Bucklen et al Nov. 27, 19452,400,849 Stearns May 2], 1946 2,430,064 Lawson Nov. 4, 1947 2,455,704Schultz Dec. 7, 1948 2,666,092 Balzer Jan. 12, 1954 2,666,829 Burkhardet al. Jan. 19, 1954

